It all started with a seemingly harmless blemish on 6-year-old Cori's skin in 2005. But soon Snoop Dogg (né Calvin Broadus), 38, and his wife, Shanté, 34, saw their daughter lose drastic amounts of weight and hair. Cori was diagnosed with lupus that year. "Shanté and I cried 1,000 times," says Snoop, whose family found strength in fighting the disease. At Cori's urging-"I wanted to help others," says the now 11-year-old-the couple talk about their crisis for the first time with PEOPLE's Jennifer Garcia.
Shanté: Every year for Cori's birthday in June, we'd go to La Jolla [Calif.] for a week. The kids [they also have two sons, Corde, 16, and Cordell, 13] would swim all day in the pool. [On our 2005 trip] Cori had a light spot on her face. I'm like, "Maybe the chlorine is bothering you, so no swimming."
When the family returned to Los Angeles, Cori saw a dermatologist.
Shanté: They gave her cream and said it was fine. The next two weeks, another spot came, she started losing weight and her hair was falling out.
Snoop: My daughter is the love of my life [he fights back tears]. When she'd lay in bed saying, "My brain hurts," it bothered me so much. I felt helpless. No power, no friends.
As Cori's condition worsened, countless medical tests yielded no diagnosis.
Shanté: No one could tell me what was wrong. They drew tons of blood and said she has old-person cells. They gave her all kinds of [meds]. But she went downhill. She was so skinny.
Meanwhile, Shanté and Snoop's marriage was faltering. On their way home from a counselor's office, Shanté's physician called with heartbreaking news.
Snoop: The counselor was helping us try to become a stronger couple.
Shanté: We were in the car and my doctor said, "I need you to come in-your daughter has cancer or lupus." I was in shock. I jumped out of the car and ran all the way to her office.
Snoop: You always think it's gonna happen to someone else. Some days in the studio, I'd just cry. It was the only zone I had to express myself.
Shanté: Without [Snoop], I don't know what I'd have done.
Days later at UCLA Medical Center, Cori was diagnosed with lupus, but her mom waited a few weeks until she felt strong enough to break the news.
Shanté: My two boys, Cori and I sat in a circle. I said, "Let's pray." I played a video about lupus, then I told her.
Cori: I was relieved [to find out].
Snoop: She's the toughest little thing I've ever met, even with the needles.
Cori underwent intensive treatment at UCLA, including powerful steroids.
Snoop: We went nearly every day for two months to find medicines that worked. The steroids would put weight on and then take it off. Sometimes Cori couldn't move her joints, and she'd ask us to massage her feet and hands.
Shanté: At one point she got hives [from a medication] and couldn't breathe. We took her to the ER. They said, "If you had waited a second longer, we don't know if she would have lived."
It took months to get her lupus under control, but with specialized pediatric care Cori's condition greatly improved.
Cori: I take liquid medicine-eight kinds in the morning and two at night every day. I can't stay in the sun long, but I feel good most of the time.
Snoop: She's on the honor roll, playing volleyball and softball, living life. She has all this joy. In the beginning lupus was winning. But now Cori is.
Shanté: It's amazing how this all turned out. We were gonna get a divorce. But we wouldn't have gotten through it [that way].
Snoop: That's what it boiled down to. Cori's lupus showed us we need to be together forever.